// This is an open source non-commercial project. Dear PVS-Studio, please check it.
// PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com

// ReSharper disable CheckNamespace
// ReSharper disable CommentTypo
// ReSharper disable IdentifierTypo
// ReSharper disable InconsistentNaming
// ReSharper disable UnusedMember.Global

/* PdfImportedObjectTable.cs --
 * Ars Magna project, http://arsmagna.ru
 */

#region Using directives

using System.Collections.Generic;

using AM;

#endregion

namespace PdfSharpCore.Pdf.Advanced;

/// <summary>
/// Represents the imported objects of an external document. Used to cache objects that are
/// already imported when a PdfFormXObject is added to a page.
/// </summary>
internal sealed class PdfImportedObjectTable
{
    /// <summary>
    /// Initializes a new instance of this class with the document the objects are imported from.
    /// </summary>
    public PdfImportedObjectTable
        (
            PdfDocument owner,
            PdfDocument externalDocument
        )
    {
        Sure.NotNull (owner);
        Sure.NotNull (externalDocument);

        Owner = owner;
        _externalDocumentHandle = externalDocument.Handle;
        _xObjects = new PdfFormXObject[externalDocument.PageCount];
    }

    readonly PdfFormXObject[] _xObjects;

    /// <summary>
    /// Gets the document this table belongs to.
    /// </summary>
    public PdfDocument Owner { get; }

    /// <summary>
    /// Gets the external document, or null, if the external document is garbage collected.
    /// </summary>
    public PdfDocument? ExternalDocument => _externalDocumentHandle.IsAlive ? _externalDocumentHandle.Target : null;

    readonly PdfDocument.DocumentHandle _externalDocumentHandle;

    public PdfFormXObject GetXObject (int pageNumber)
    {
        return _xObjects[pageNumber - 1];
    }

    public void SetXObject (int pageNumber, PdfFormXObject xObject)
    {
        _xObjects[pageNumber - 1] = xObject;
    }

    /// <summary>
    /// Indicates whether the specified object is already imported.
    /// </summary>
    public bool Contains (PdfObjectID externalID)
    {
        return _externalIDs.ContainsKey (externalID.ToString());
    }

    /// <summary>
    /// Adds a cloned object to this table.
    /// </summary>
    /// <param name="externalID">The object identifier in the foreign object.</param>
    /// <param name="iref">The cross reference to the clone of the foreign object, which belongs to
    /// this document. In general the clone has a different object identifier.</param>
    public void Add (PdfObjectID externalID, PdfReference iref)
    {
        _externalIDs[externalID.ToString()] = iref;
    }

    /// <summary>
    /// Gets the cloned object that corresponds to the specified external identifier.
    /// </summary>
    public PdfReference this [PdfObjectID externalID] => _externalIDs[externalID.ToString()];

    /// <summary>
    /// Maps external object identifiers to cross reference entries of the importing document
    /// {PdfObjectID -> PdfReference}.
    /// </summary>
    readonly Dictionary<string, PdfReference> _externalIDs = new Dictionary<string, PdfReference>();
}
